Radar Transceiver
United States Patent Application: 0150002328
| Applicant: |
| Name | City | State | Country | Type |
NXP B.V. |
Eindhoven | |
NL | |
|
|---|
Abstract
The application refers to a radar transceiver comprising a set of
transmitters (TX1, . . . , TXn) for transmitting radar chirps to targets,
a set of receivers (RX 1, . . . , RXn) for receiving reflected chirps
from the targets, a timing engine (1) coupled to the set of transmitters
(TX1, . . . , TXn) and to the set of receivers (RX1, . . . , RXn) and
adapted to transmit a first set of control signals to the set of
transmitters (TX1, . . . , TXn) and to the set of receivers (RX1, . . . ,
RXn). The timing engine (1) is further coupled to a computing unit (4).
The timing engine (1) is adapted to receive a second set of control
signals generated by the computing unit (4) and transmitted via a bus.
The radar transceiver further comprises a sweep control unit (2) coupled
to the timing engine (1) and adapted to receive a first control signal
and a second control signal from the timing engine (1), the first control
signal indicating a precise start time of a chirp and the second control
signal indicating a precise reset time for resetting the chirp. The sweep
control unit (2) is further coupled to a controlled Phase Locked Loop
(PLL) (3) adapted to generate a local oscillator (Master LO) signal which
is adapted to be inputted to both each member of the set of transmitters
(TX1, . . . , TXn) and each member of the set of receivers (RX1, . . . ,
RXn).
BACKGROUND OF THE INVENTION
[0002] Radar sensors featuring high angular resolution normally rely on
large antenna apertures. This can be achieved with the use of a
dielectric lens in front of a small number of antenna elements, or with a
large number of receiving (RX) elements in a phased array configuration
as e.g. Bosch LRR3. Lens-antenna based techniques have the disadvantage
of a small angular field-of-view of +10 degrees, making this approach
less suitable for short- and middle-range radar applications where a
larger field of view is required i.e. larger than .+-.60.degree. degrees.
In the following description the term RX is used to indicate a receiver
and the term TX is used to indicate a transmitter, together with their
plural forms RXs and TXs, respectively.
[0003] The large RX antenna array, on the other hand, leads to a large
sensor physical size which is a drawback in many practical circumstances
e.g. placement behind the bumper, etc.
[0004] It has been shown that the application of Multiple Input Multiple
Output (MIMO) techniques that combines a relatively small number of RXs
e.g. 4 with a small number of TXs e.g. 4 [Feger-2009 `A 77-GHz FMCW MIMO
Radar Based on an SiGe Single-Chip Transceiver`,
Reinhard Feger et al., IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, MAY 2009, pp. 1020-1035] provides a larger "effective" receiving aperture, effectively
the aperture of 16 receiving antennas, without the drawbacks mentioned
above, meaning that the field of view is kept relatively large and the
physical size is comparable to a small array of 4 RXs. The MIMO technique
described above works by sequentially switching the TXs while the RXs
acquire and store data, so that a set of measurements for all
combinations of TX and RX antennas is obtained after the data acquisition
cycle completes [TX1, RX1, RX2, . . . ], [TX2, RX1, RX2, . . . ]. The
radar processing is then completed by post-processing the set of measured
results for the different TX1, . . . , TXn possibilities.
[0005] An alternative technique for MIMO radar signal acquisition and
processing is described in US2012/0001791 and it is shown in FIG. 1. In
this application the phase of a TX path TX0 is binary toggled from chirp
to chirp, whereas the phase of the second TX path TX1 is kept constant
from chirp to chirp. The data acquisition process is simultaneous for TX0
and TX1, instead of sequential as in the method proposed by Feger. The
phase toggling in path TX0 allows the signal from the two TXs antennas to
be separated in subsequent signal processing steps.
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SUMMARY OF THE INVENTION
[0021] Hence, it is a need for an improved radar system.
[0022] It is therefore an object of the invention to provide a radar
transceiver system comprising [0023] a set of transmitters for
transmitting radar chirps to targets, [0024] a set of receivers for
receiving reflected chirps from the targets, [0025] a timing engine
coupled to the set of transmitters and to the set of receivers and
adapted to transmit a first set of control signals to the set of
transmitters and to the set of receivers, the timing engine being further
coupled to a computing unit, the timing engine being adapted to receive a
second set of control signals generated by the computing unit and
transmitted via a bus, [0026] a sweep control unit coupled to the timing
engine and adapted to receive a first control signal and a second control
signal from the timing engine, the first control signal indicating a
start time of a chirp and the second control signal indicating a reset
time for resetting the chirp, the sweep control unit being further
coupled to a controlled Phase Locked Loop (PLL) adapted to generate a
local oscillator signal which is adapted to be inputted to both each
member of the set of transmitters and each member of the set of
receivers.
[0027] In this way, the chirps generation is precisely controlled by the
timing engine and the chirps are generated by the PLL under the direct
control of the sweep control unit. Hence, the use of the SPI is avoided
in the acquisition mode and the chirps are generated with a more precise
timing control.
